JP3689097B2 - Charged beam drawing apparatus and drawing method - Google Patents

Description

  The present invention relates to a multi-beam type charged beam drawing apparatus and a drawing method having a plurality of charged beam optical systems.

  Conventionally, an electron beam drawing apparatus has been widely used for advanced device development. This electron beam drawing apparatus draws a desired figure on a sample by deflecting an electron beam electromagnetically or electrostatically. However, when the beam is simply deflected, a deflection distortion as shown in FIG. Therefore, prior to drawing, it is necessary to adjust the drawing position as shown in FIG.

  The drawing position is generally adjusted as follows. That is, the stage is moved by the beam deflection distance, and the voltage or current applied to the deflection electrode or coil is determined so that the mark provided on the stage can be detected. At this time, as marks used for beam adjustment, there are marks that use the difference in atomic number between the mark and the base substrate and the difference in the reflected electron rate due to unevenness. The size of the beam deflection region is usually from 100 μm to several mm. When drawing is performed in a range exceeding the deflection region, drawing is performed by moving the stage into the beam deflection region.

  In the figure, 201 indicates a deflection region having distortion, and 202 indicates a deflection region in which distortion is corrected.

  In manufacturing a semiconductor device, overlay exposure is generally performed on a base pattern formed on the same substrate. In such a case, it is necessary to detect the position of the mark provided on the base substrate. As the position detection mark, there is a mark using the difference in the reflected electron rate due to the unevenness of the mark or the difference in atomic number between the mark and the base substrate, as in the adjustment of the drawing position. The mark position is detected by scanning the mark with an electron beam and measuring the intensity of the reflected electron signal.

  In recent years, technical development of electron beam lithography systems aiming at high throughput has been performed. Among these, the multi-beam method having a plurality of electron beam optical systems is promising. In this multi-beam type electron beam drawing apparatus, since drawing is performed with a plurality of beams instead of drawing with one beam, it is expected that the drawing throughput will be remarkably improved.

  Since the multi-beam method requires beam adjustment in each optical system, it takes an enormous amount of time when individual beam adjustments are performed sequentially. For this reason, in the adjustment of the drawing position and the overlay exposure, it is necessary to simultaneously detect the marks for a plurality of beams. However, if mark detection is performed simultaneously with a plurality of beams, there is a problem that accurate alignment cannot be performed due to the influence of reflected electrons from other marks.

  That is, as shown in FIG. 26, one electron optical system includes an electron gun 1, a beam blanking system 3, 4, a beam deflection system 5a, 5b, a beam adjusting lens system 2a, 2b, 2c, and a reflected electron detector. It consists of six. FIG. 27 shows an overview of the beam adjustment mark. FIG. 27A is a plan view and FIG. 27B is a cross-sectional view. When the mark position is detected, as shown in FIG. 28, the mark 10 is provided in the drawing region 12 corresponding to each electron beam optical system 13, the beam scanning is simultaneously performed on the plurality of marks 10, and the beam scanning position is detected. The mark position is detected from the reflected electron signal corresponding thereto. In the conventional electron beam optical system, as shown in FIG. 29, when a mark is detected simultaneously with a plurality of electron beams 7, reflected electrons 8 from the original mark and reflected electrons 9 from other marks are used. Enters the detector 6 from the lateral direction, so that it is difficult to detect individual mark positions.

  As countermeasures, there have been proposed a method of shifting the position detection timing for each electron beam optical system and a method of aligning a plurality of chips without performing alignment for each chip. However, these methods have a problem in that the apparatus configuration is complicated, and it takes a longer time to detect the mark than in the case where mark detection is simultaneously performed in all electron beam optical systems.

  On the other hand, since the multi-beam method is not a batch exposure like an optical stepper or an X-ray exposure, it is necessary to adjust the beam in each lens barrel. In the case of a conventional electron beam drawing apparatus having only one electron beam source, only one mark for drawing position adjustment is used. However, in a multi-beam drawing apparatus, since many beam adjustments must be performed, when one mark is shared, it takes a lot of time for beam adjustment. For this reason, in the multi-beam drawing apparatus, it is necessary to employ a method of having a reference mark corresponding to each electron beam optical system and performing beam adjustment for each lens barrel.

  However, in the method of performing beam adjustment for each lens barrel using the reference marks corresponding to the electron beam optical systems described above, the following problems occur. That is, the chip size varies depending on the type of device, and one electron beam source does not necessarily correspond to one chip. As shown in FIG. 30, when drawing a pattern 213 larger than the arrangement pitch of the electron beam optical system 211 (more specifically, the drawing region 212 by one electron beam optical system), a plurality of electron beam optical systems 211 are drawn. One pattern 213 is drawn using. For example, when the electron beam optical system is arranged at a pitch of 10 mm, when the chip size exceeds 20 mm square, drawing is performed using four or more electron beam optical systems. Further, when drawing a sample having a side exceeding 150 mm, such as a photomask, writing is performed with a larger number of electron beams.

  Here, there is no problem when the position of the reference mark 214 of each electron beam optical system is ideally arranged as shown in FIG. However, in actuality, it should be distorted as shown in FIG. 31B, and the pattern drawn based on this reference mark will be distorted as shown in FIG. In this case, when one chip is drawn with a plurality of electron beam sources, as shown in FIG. 33, there is a problem in the connection accuracy at the drawing region boundary between adjacent electron beam optical systems. Reference numeral 215 denotes one drawing area, 216 denotes a drawing area boundary, and 217 denotes a drawing pattern.

  For the drawing accuracy, the connecting accuracy of the deflection regions is important. This is because even if the minimum dimension of the beam is small, a figure as designed data cannot be drawn on the sample if the connection accuracy is poor.

  As described above, the multi-beam method described above is not a batch exposure like a stepper, so that it is necessary to adjust the beam in each lens barrel. Since each electron beam source of the multi-beam drawing apparatus has an independent electron optical system, there is a problem in that even if beam adjustment is performed individually, the connection accuracy is deteriorated between different electron beam sources. In addition, the chip size varies depending on the type of device, and it is not always reasonable to make one electron beam source correspond to one chip. Although it is inevitable that one chip is drawn with a plurality of electron beam sources, there arises a problem that connection accuracy in the beam deflection boundary region is deteriorated due to a difference in beam characteristics for each electron beam source.

  As described above, in a conventional multi-beam type electron beam drawing apparatus, when drawing a pattern that requires a drawing area larger than the arrangement pitch of each electron beam optical system, the drawn pattern is distorted or adjacent. There has been a problem that the connecting accuracy of the electron beam writing region is deteriorated.

  These problems are not limited to the electron beam drawing apparatus, but can be similarly applied to an ion beam drawing apparatus using an ion beam as a charged beam.

  The present invention has been made in consideration of the above-described circumstances, and the object of the present invention is to eliminate multi-beam charge beams at the boundary of the drawing area and improve the drawing accuracy. To provide a drawing apparatus and a drawing method.

(Constitution)
In order to solve the above problems, the present invention adopts the following configuration.

  (1) In a multi-beam type charged beam drawing apparatus having a plurality of charged beam optical systems, reference mark groups respectively provided on the sample table corresponding to the plurality of charged beam optical systems, and movement on the sample table Means for moving the reference mark group, means for scanning the moved reference mark with a charged beam, measuring the position of each reference mark, means for storing the relative positional relationship of each measured reference mark, Characterized in that it comprises means for correcting the position of the drawing area of each charged beam based on the relative positional relationship of each stored reference mark, and means for drawing based on the corrected drawing position. To do.

  Further, a multi-beam type charged beam drawing apparatus having a plurality of charged beam optical systems, wherein the drawing position is corrected by using a reference mark group provided on the sample stage corresponding to each charged beam optical system. In the charged beam writing method, the mark position detection using a plurality of charged beam optical systems, the mark position detection using a reference mark of an adjacent charged beam optical system, and the relative position of the reference mark group The method includes a step of calculating a positional relationship, a step of correcting a position of a drawing region of each charged beam optical system based on the calculation result, and a step of drawing at the corrected drawing position.

  (2) In a multi-beam type charged beam drawing method in which drawing is performed using a plurality of charged beam sources, drawing is performed such that deflection boundary regions of adjacent charged beam sources overlap each other. Furthermore, the irradiation amount correction of the overlapping area is performed.

(Function)
With the configuration of (1) above, after the mark position is detected by each charged beam optical system, the mark position is detected using the reference mark of the adjacent charged beam optical system, whereby the adjacent charged beam is detected. By measuring the relative positional relationship with the drawing area of the optical system and performing drawing by correcting the drawing position in actual drawing, the connecting accuracy is improved and high-precision drawing can be performed.

  With the configuration of (2) above, drawing is caused by a difference in beam characteristics for each charged beam source by overlapping the deflection region boundary between adjacent charged beam sources and correcting the irradiation amount of the overlapping region. It is possible to eliminate the region shift and improve the drawing accuracy.

  As described above in detail, according to the present invention, even in the case of pattern drawing that requires a drawing region larger than the arrangement pitch of each charged beam optical system in a multi-beam type drawing apparatus, drawing is performed with a plurality of charged beam optical systems. Even in the case of performing the above, particularly the connecting accuracy of the charged beam at the boundary of the drawing region is improved, and high-precision drawing can be performed.

  Before describing embodiments of the invention, reference examples of the present invention will be described.

(Reference example)
FIG. 1 is a diagram showing one electron beam optical system in a multi-beam type electron beam drawing apparatus according to a reference example of the present invention. This electron beam optical system includes an electron gun 1, beam blanking systems 3 and 4, beam deflection systems 5a and 5b, beam adjusting lens systems 2a, 2b and 2c, and a reflected electron detector 6.

  When performing mark position detection, beam scanning is performed on the mark corresponding to each electron beam. However, in the conventional electron beam optical system, the reflected electron detector is exposed as shown in FIG. For this reason, when a mark is detected with a plurality of electron beams, reflected electrons from other marks enter the detector from the lateral direction, making it difficult to detect individual mark positions.

  On the other hand, in this reference example, a collimator 11 is attached to the backscattered electron detector 6 as shown in FIG. Therefore, as shown in FIG. 2, even when the positions of the marks 10 are simultaneously detected with a plurality of beams 7, the reflected electrons 8 from the corresponding marks 10 are detected from the other marks 10 while being detected in the same manner as in the prior art. Intrusion of the reflected electrons 9 can be prevented. Even when the beam is deflected within a range of several mm as in the correction of deflection distortion, only the reflected electrons 9 from other marks 10 can be removed by adjusting the aperture angle.

  As described above, in the present reference example, the reflected electrons 9 from the other marks 10 can be removed by the collimator 11 attached to the reflected electron detector 6. For this reason, even when the alignment is simultaneously performed by a large number of electron beams 7, the mark position can be detected independently by each electron beam, and the drawing time can be greatly shortened.

  Next, a specific example will be described from the reference example.

(Reference Example 1-1)
FIG. 3 is a diagram showing a schematic configuration of a multi-beam type electron beam drawing apparatus used in this reference example. In the figure, 13 is an electron beam optical system, 14 is a sample, 15 is a sample chamber, 16 is a stage, 17 is a reference mark, 18 is a control circuit, 19 is a control computer, and 50 is a stage length measurement system.

  The accelerating voltage of the drawing apparatus is 10 kV. Further, the drawing possible range is 150 mm square, and a total of 225 electron beam optical systems are arranged at 15 × 15 pitches at a pitch of 10 mm. The beam deflection system 13 has a main / sub / two-stage configuration based on electrostatic deflection, and the size of each deflection region is 500 μm for the main deflection and 100 μm for the sub-deflection. The drawing area of each electron beam optical system 13 is ± 5 mm with the electron gun as the center, and this drawing area is drawn with 400 main deflection areas.

  On the stage 16, a beam adjustment mark is provided as shown in FIG. There are 15 × 15 marks corresponding to each electron beam optical system 13 so as to form a pair, and one mark is provided in the drawing region of each electron beam optical system 13. The mark has a cross shape as shown in FIG. 27, and was formed by digging a Si substrate by light exposure and plasma etching. The size of the mark is 100 μm on one side, the width is 5 μm, and the depth is 2 μm.

  In this reference example, the collimator 11 is provided in the backscattered electron detector 6 of each electron beam optical system 13 as shown in FIG. The collimator 11 has a cylindrical shape.

  Here, deflection distortion correction of the multi-beam type electron beam drawing apparatus will be described with reference to FIG. The deflection distortion correction was performed as follows.

  First, the main deflection area of 500 μm is divided into 50 μm meshes, and the stage is moved so that the reference mark 20 is on the lattice point. The beam is then deflected and scanned over the mark 20. The deflection voltage at the mark center is calculated from the beam deflection amount and the mark position. As indicated by reference numeral 22 in the figure, the reference mark is sequentially moved to store the deflection amount. The same operation was performed for the sub-deflection area having a size of 100 μm square. At this time, the mesh size was 5 μm.

  As a result of the above-described deflection distortion correction being simultaneously performed on 15 × 15 beams, each electron beam optical system could be performed without any problem. At this time, the time required for beam adjustment was 1 minute. It took 225 minutes (about three and a half hours) when beam adjustment was performed for each of 15 × 15 beams. On the other hand, in this reference example, the time required for beam adjustment could be reduced to 1/225 as a result of simultaneously performing 15 × 15 beams. Moreover, as a result of performing normal drawing after adjusting the deflection distortion, high-precision drawing could be performed.

(Reference Example 1-2)
In this reference example, the collimator 23 is provided in the backscattered electron detector 6 of each electron beam optical system as shown in FIG. The collimator 23 in this reference example has a cylindrical shape as in the reference example 1-1, but is provided not to each backscattered electron detector 6 but to surround one electron beam optical system. Here, alignment with respect to the base pattern formed on the Si substrate was performed by this multi-beam type electron beam drawing apparatus.

  As shown in FIG. 6, a plurality of chips 25 are arranged on the wafer 26. The chip size is 10 mm square, and alignment marks 24 are arranged at the four corners of each chip 25. These marks 24 are concave marks in which a Si substrate is dug by light exposure and plasma etching. The size of the mark 24 is 100 μm on one side, the width is 5 μm, and the depth is 2 μm. At the time of drawing, one chip is simultaneously drawn by each electron beam optical system. The alignment is performed as follows.

  The wafer position on the stage is confirmed by a wafer alignment mark 27 provided at a location different from the chip 25. Next, the mark position in each chip 25 is calculated from the chip layout information on the wafer 26. Based on the calculated mark position of each chip 25, the stage is moved to detect the mark position. In this way, the four mark positions in the chip 25 are sequentially detected. Here, since the chips are arranged at the same pitch as that of the electron beam optical system, it is possible to detect the mark position simultaneously with 15 × 15 beams without doing anything special.

  As a result of detecting the alignment mark 24 for 15 × 15 beams at the same time, it was possible to perform alignment for each electron beam optical system without any problem. At this time, the time required to adjust one beam was 1 minute, and a total of 4 minutes was required for one chip. When the beam adjustment is performed for each of 15 × 15 beams, it takes about 12 hours, whereas in this reference example, the time required for alignment as a result of the simultaneous execution of 15 × 15 beams. Was reduced to 1/225. In addition, as a result of performing normal drawing after alignment, high-precision drawing could be performed.

(Reference Example 1-3)
In this reference example, a shield plate 31 having a hole as shown in FIG. 7 was used as a collimator for the backscattered electron detector of each electron beam optical system. The collimator 31 was placed between the sample and the electron beam optical system as shown in FIG. In FIG. 7, 28 is an electron beam passage hole, 29 is an opening for a backscattered electron detector, and 30 is a drawing region of the electron beam optical system.

  When alignment drawing was performed using the collimator 31 in the same manner as in Reference Example 1-2, alignment could be performed without any problem. In addition, as a result of performing normal drawing after alignment, high-precision drawing could be performed.

  The details of the present invention will be described below with reference to the illustrated embodiments.

(First embodiment)
Next, a first embodiment of the present invention will be described with reference to the flowchart of FIG. Here, for the sake of simplicity, an electron beam drawing apparatus will be described in which an electron beam source has a total of 64 arrays of 8 × 8 as shown in FIGS.

  First, this embodiment is characterized by including the following means.

  (1) One electron beam optical system is selected from a plurality of electron beam optical systems (S1).

  (2) The beam of the selected electron beam optical system is turned off (S2).

  (3) Mark detection is sequentially performed with an electron beam optical system other than the selected one (S3).

  (4) The interference of the reflected particles from other marks in the selected electron beam optical system is measured (S4).

  (5) The above operation is repeated for all electron beam optical systems (S5, S6).

  (6) The electron beam optical systems without interference are grouped (S7).

  (7) One of the grouped electron beam optical systems is selected (S8).

  (8) A plurality of mark positions are detected simultaneously using the selected electron beam optical system (S9).

  (9) The above operation is repeated for all groups (S10, S11).

  In step S4, the interference of reflected electrons from other electron beams is measured. For example, when the selected electron beam optical system is 35 in the figure and the drawing region of the electron beam optical system is 34 in the figure, this beam is blanked. At this time, when mark detection is performed with the electron beam in the row indicated by 36 in the figure, for example, in the case of an electron beam corresponding to 37 in the adjacent figure, the reflected electrons are detected by the electron beam optical system in the figure. It jumps into the vessel (Fig. 10 (a)). On the other hand, in the other electron beam optical system shown in FIG. 38, the reflected electrons are not detected, or even if they are detected, the amount is the same level as the noise (FIG. 10B).

  Next, an electron beam optical system is sequentially selected from the electron beam optical systems in the 39th row in the figure, and the interference of reflected electrons is measured in the same manner (FIG. 10C). Here, for example, reflected electrons interfere in the electron beam optical system 40 in the adjacent figure, but reflected electrons are not detected in the other electron beam optical systems shown in 41 in the figure (FIG. 11 (d)). . In this way, as shown by 43 in the figure, it can be obtained in the minimum unit with which the reflected electrons interfere. In this case, since marks cannot be detected at the same time in the area indicated by 43 in the figure, settings are made so as to be in different groups (34, 37, 40, and 42 in the figure) (FIG. 11 (e)).

  In step S7, as shown in FIG. 12, the minimum unit of 43 in the figure is applied to the entire electron beam array. As a result, an electron beam group free from interference of reflected electrons can be made into four groups.

  In the groups obtained in S1 to S7, even if the mark position is detected at the same time, there is no interference of reflected electrons, and the mark position can be detected without any problem. In this case, four times are required to perform mark detection in all electron beam optical systems. As a result, the time required for mark detection can be reduced to 1/16 compared with the case where mark detection is performed for all 64 electron beam optical systems. As a result, beam adjustment and alignment can be performed simultaneously with a plurality of electron beam optical systems, and the drawing time can be greatly shortened. Here, in order to simplify the description, the electron beam optical system is an 8 × 8 array. However, even if the electron beam optical system is a larger 10 × 10 array, mark detection is performed in the same manner. be able to.

  Next, a more specific embodiment of the first embodiment will be described.

(Embodiment 1-1)
The schematic configuration of the multi-beam drawing apparatus used in the present embodiment is as shown in FIG. The acceleration voltage of this device is 10 kV. Further, the drawing possible range is 80 mm square, and 8 × 8, a total of 64 electron beam optical systems are arranged at a pitch of 10 mm. The beam deflection system has a main / sub-stage configuration by electrostatic deflection, and the size of each deflection region is 500 μm for the main deflection and 100 μm for the sub-deflection. The drawing area of each electron beam is ± 5 mm centered on the electron gun, and this drawing area is drawn with 400 main deflection areas.

  On the stage, a beam adjustment mark is provided as shown in FIG. There are 8 × 8 marks corresponding to each electron beam optical system so as to form a pair, and one mark is provided in the drawing region of each electron optical system. The shape and size of the mark is the same as described with reference to FIG.

  In this embodiment, deflection distortion correction of a multi-beam type electron beam drawing apparatus is performed. First, prior to deflection distortion correction, electron beam optical systems are grouped. This will be described below with reference to FIGS.

  1) Select the electron beam optical system (35 in the figure).

  2) Blank the beam of this electron beam optical system.

  3) Mark detection is performed by the electron beam optical system in the row indicated by 36 in the figure.

  4) As a result, in the case of the electron beam optical system corresponding to 37 in the adjacent figure, the reflected electrons were detected by the reflected electron detector of the electron beam optical system 35 in the figure.

  5) On the other hand, in the other electron beam optical system indicated by 38 in the figure, almost no reflected electrons were detected.

  6) Next, an electron beam optical system was sequentially selected from the electron beam optical systems in the 39th row in the figure, and the interference of reflected electrons was measured in the same manner. Here, the reflected electrons interfered with the electron beam 40 in the adjacent figure, but the reflected electrons were not detected in the other electron beam optical systems shown in 41 in the figure.

  7) As a result of the above, the minimum unit with which the reflected electrons composed of the four electron beam drawing regions as shown by 43 in FIG.

  8) The area indicated by 43 in the figure was set to be in different groups (34, 37, 40, and 42 in the figure).

  9) The minimum unit of 8) was repeatedly arranged in an 8 × 8 array as shown in FIG.

  In the manner described above, four groups having 16 electron beam optical systems were created in each group, and the information was stored in the control computer.

  Next, deflection distortion correction was performed as follows.

  1) As shown in FIG. 4, the main deflection area of 500 μm is divided into 50 μm meshes, and the stage is moved so that the reference marks are on the lattice points.

  2) Select 16 beams of the first group.

  3) 16 beams are deflected simultaneously and scanned over the mark.

  4) The deflection voltage at the mark center is calculated from the beam deflection amount and the mark position.

  5) The operations of 3) to 4) are repeated for the second group to the fourth group.

  6) The reference mark is moved in the same manner as 22 in FIG. 4, and the operations 2) to 5) are repeated.

  7) The same operation as in 1) to 7) is performed for the sub-deflection area having a size of 100 μm square. At this time, the mesh size was 5 μm.

  As a result of performing the above operation on 8 × 8 beams with 16 beams from the first to the fourth groups at the same time, it was possible to correct the deflection distortion of each electron beam optical system without any problems. . At this time, the time required to adjust one beam was 1 minute, and the time required to correct the deflection distortion of each group of 8 × 8 beams by 4 groups was 4 minutes. When the beam adjustment is performed for each 8 × 8 beams, it takes about one hour. In the present embodiment, however, 8 × 8 beams are simultaneously performed, and as a result, deflection distortion correction is required. The time was reduced to about 1/16. In addition, as a result of performing normal drawing after correcting the deflection distortion, high-precision drawing could be performed.

(Embodiment 1-2)
In this embodiment, the alignment with respect to the base pattern formed on the Si substrate was performed by a multi-beam type electron beam drawing apparatus.

  The chip size is 10 mm square, and alignment marks are arranged at the four corners of the chip as shown in FIG. This mark is a concave mark in which a Si substrate is dug by light exposure and plasma etching. The mark has a size of 100 μm on one side, a width of 5 μm, and a depth of 2 μm. At the time of drawing, one chip is simultaneously drawn by each electron beam optical system. The alignment is performed as follows.

  First, a wafer alignment mark provided in an area other than the chip is optically detected to confirm the wafer position on the stage. Next, the mark position in each chip is calculated from the chip layout information on the wafer. Based on the calculated mark position of each chip, the stage is first moved to measure the first mark position, and the mark position of each chip is sequentially detected for each of the first to fourth groups. Subsequently, the second to fourth mark position measurements were performed in the same procedure. Here, since the chip is arranged at the same pitch as the electron beam optical system, the stage may be moved four times in accordance with the mark position in the chip.

  As a result of the detection of the alignment marks being performed simultaneously for each of four groups of 8 × 8 beams, alignment of each electron beam optical system could be performed without any problem. At this time, the time required to adjust one beam was 15 seconds, and a total of 1 minute was required for one chip. As a result, the time required to align the 8 × 8 beams was 4 minutes. When the beam adjustment is performed for each of 8 × 8 beams, it takes about one hour. In the present embodiment, the time required for alignment is the result of performing the operation for 8 × 8 beams at the same time. Was reduced to about 1/16. In addition, as a result of performing normal drawing after alignment, high-precision drawing could be performed.

(Embodiment 1-3)
In the present embodiment, grouping of electron optical systems is performed by computer simulation. In actual device fabrication, a GaAs substrate or a heavy metal such as W can be used as a sample. If the electron beam optical system is grouped by a computer, it is not necessary to group various types of substrates every time the substrates are changed.

  First, the multi-beam electron beam drawing apparatus used in this embodiment was reproduced on a computer program. Here, as shown in FIG. 13, only one-dimensional calculation was performed.

  First, when electrons accelerated to 10 kV are incident on the Si substrate, when mark detection is sequentially performed by the electron beam optical system in the row 46 in the figure, the degree of interference in the electron beam optical system 45 in the figure is shown. Was calculated. Here, the reflected electrons 9 from the most adjacent mark were detected by a reflected electron detector 45 of the electron beam optical system in the figure. On the other hand, it was found that the reflected electrons 9 'from the marks other than the most adjacent mark were hardly detected by the reflected electron detector 45 of the electron beam optical system in the figure. As a result of enlarging the calculation results in the one-dimensional space into two dimensions, the same grouping as in FIG. 12 could be performed.

  When grouping by a computer, even when a GaAs substrate or a heavy metal such as W is assumed as a sample, the range covered by the reflected electrons can be obtained from the data of the amount and angle of the reflected electrons by Monte Carlo calculation. . For this reason, it is no longer necessary to group various types of substrates each time the substrates are changed.

  When electron beams were grouped by the above method and alignment drawing was performed in the same manner as in Embodiment 1-2, alignment could be performed without problems. In addition, as a result of performing normal drawing after alignment, high-precision drawing could be performed.

  The present invention does not limit the drawing apparatus and the drawing method. In addition to those shown in the embodiment, for example, the present invention can also be applied to a drawing apparatus that divides one beam into a plurality of parts by an aperture. Further, the present invention does not limit the shape or type of the mark. In addition to those shown in the embodiment, for example, convex marks using heavy metals can be applied. In addition, various modifications can be made without departing from the scope of the present invention.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. Here, in order to simplify the description, an electron beam drawing apparatus will be described in which the electron beam source has a total of nine arrays of 3 × 3. At this time, each electron beam optical system is provided with a reference mark corresponding to each electron beam optical system, as shown in FIG. In the figure, 7 is an electron beam, 10 is a mark, 13 is an electron optical system, and 52 is a drawing region by one electron optical system.

  It is difficult to make the position of the reference mark in an ideal arrangement as shown in FIG. Actually, it is distorted as shown in FIG. When such a reference mark is used, the reference mark position is deviated. Therefore, when one chip is drawn by a plurality of electron beam optical systems, pattern position deviation occurs at the drawing area boundary of each electron beam optical system. To do.

  In this embodiment, not only the measurement of the position of the reference mark corresponding to each electron beam optical system but also the reference mark position of the adjacent electron beam optical system is measured to measure the relative positional deviation of each reference mark. ing. For example, it is assumed that each reference mark is shifted as shown in FIG. 32 when the reference mark in the first row and the first column in the figure is the origin. Here, in order to simplify the description, 100 μm is represented as 1.

  First, the mark is moved to the center of each electron beam optical system to detect the mark position. Next, as shown in FIG. 15, the mark is moved in the Y direction by the pitch of the electron beam optical system, and the position of the reference mark of the adjacent electron beam optical system is measured. Further, the stage is moved in the reverse direction, and the position of the reference mark of the adjacent electron beam optical system is measured. In this way, the amount of deviation in the XY direction of the reference mark position between the rows can be obtained for each column. In the figure, 47 indicates a fixed electron beam arrangement, and 48 indicates a moved stage position.

  Here, assuming that each electron beam optical system in the first row is a reference (0, 0), the position of the reference mark in the column direction can be expressed as follows.

1st column 2nd column 3rd column 1st row (0,0) (0,0) (0,0)
2nd line (1, 0) (-1, 0) (0, 0)
3rd line (0,1) (0,1) (1, -1) (× 100μm)
Next, as shown in FIG. 16, the stage is moved also in the X direction, and the mark position deviation between the columns is measured in the same manner as between the rows. Here, it is assumed that the positional deviation of the reference mark in the first row can be expressed as follows with reference to each electron beam optical system in the first column.

1st column 2nd column 3rd column 1st row (0,0) (1,0) (0, -1) (× 100 μm)
If this value is added to the first measurement result, the relative position of each reference mark with the reference mark in the first row and first column in the figure as the origin can be obtained.

1st column 2nd column 3rd column 1st row (0,0) (1,0) (0, -1)
2nd line (1, 0) (0, 0) (0, -1)
3rd line (0,1) (1,1) (1, -2) (× 100μm)
If the position of the drawing area is corrected based on this result, the positional deviation of the pattern at the drawing area boundary due to the difference in the reference marks of the electron beam optical systems can be reduced. In the above example, in order to make the relative displacement of the reference mark zero, the drawing position may be corrected as follows.

1st column 2nd column 3rd column 1st row (0, 0) (-1, 0) (0, 1)
2nd line (-1, 0) (0, 0) (0, 1)
3rd line (0, -1) (-1, -1) (-1,2) (× 100 μm)
The drawing position is corrected by changing the amount of beam deflection in each electron beam optical system. As a result, the corrected drawing position can be adjusted without overlapping with the drawing region of the adjacent electron beam optical system, as indicated by 56 in FIG. In the figure, 55 is a drawing position before correction, and 56 is a drawing position after correction.

  In this way, it is possible to improve the connecting accuracy even at the drawing region boundary of each electron beam optical system. Further, since adjustment of the beam deflection distortion of each electron beam optical system and mark detection may be performed for each electron beam optical system, the drawing throughput of the multi-beam drawing apparatus can be improved. Note that. Here, in order to simplify the explanation, a 3 × 3 array of electron beams is used. However, even in the case of a 100 × 100 array having a larger electron beam, the drawing area can be similarly corrected. .

  Next, a more specific embodiment of the second embodiment will be described.

(Embodiment 2-1)
The schematic configuration of the multi-beam drawing apparatus used in the present embodiment is as shown in FIG. The configuration of each electron beam optical system is the same as that shown in FIG.

  The accelerating voltage of the drawing apparatus is 10 kV. Further, the possible drawing range is 80 mm square, and 8 × 8, a total of 64 electron beam optical systems are arranged at a pitch of 10 mm. The beam deflection system has a main / sub-stage configuration by electrostatic deflection, and the size of each deflection region is 500 μm for the main deflection and 100 μm for the sub-deflection. The drawing area of each electron beam optical system is ± 5 mm centered on the electron gun, and this drawing area is drawn with 400 main deflection areas.

  When the mark position is detected, the information is sent to the control computer and stored. After the mark detection, the positional deviation of each reference mark is calculated based on the stored mark position information. Thereafter, the position of the drawing area of each electron beam optical system is corrected, and the correction information is sent to the control circuit. At the time of drawing, the drawing data is sent from the control computer to the drawing control circuit of each electron beam optical system. At this time, the drawing position is corrected based on the correction data of the drawing area.

  On the stage, a beam adjustment mark is provided as in FIG. Although FIG. 14 is represented by a 3 × 3 array, there are 8 × 8 marks corresponding to each electron beam optical system so as to form a pair, and one mark is provided in the drawing region of each electron beam optical system. Provided. The mark has a cross shape as shown in FIG. 27, and was formed by digging a Si substrate by light exposure and plasma etching. The size of the mark is 100 μm on one side, the width is 5 μm, and the depth is 2 μm.

  In the present embodiment, an 80 mm square photomask is drawn. First, in each electron beam optical system, distortion correction of the main and sub deflection regions was performed using the respective reference marks. Next, the drawing area of each electron beam optical system was corrected as follows.

1) First, the mark is moved near the center of each electron beam optical system, and the mark position is detected.

2) Next, as shown in FIG. 18A, the mark is moved in the Y direction by the pitch (10 mm) of the electron beam optical system, and the position of the reference mark of the adjacent electron beam optical system is measured. In the figure, 51 is an electron gun, and 52 is a drawing region by one electron gun.

3) Next, move the stage by −10 mm in the opposite direction to 2), and measure the position of the reference mark of the adjacent electron beam optical system. Thereby, the deviation | shift amount of the XY direction of the reference mark position for every row | line can be calculated | required. Here, as shown in FIG. 18B, the position of the reference mark in the column direction is calculated with reference to each electron beam optical system in the first row indicated by 53 in the figure.

4) Next, the stage is returned to the original position, the mark is moved by 10 mm in the X direction as in the Y direction, and the position of the reference mark of the adjacent electron beam optical system is measured.

5) As in 3), the 10 mm stage is moved in the opposite direction, and the reference mark position of the adjacent electron beam optical system is measured. Here, the position of the reference mark in the row direction was calculated using each electron beam optical system in the first column as a reference.

6) The relative positions of the respective reference marks could be obtained by the operations 1) to 5).

7) The drawing area position of each electron beam optical system was calculated in the same manner as in FIG. 17 so as to cancel the relative positional deviation of the reference marks.

8) The above calculation results were converted into beam deflection data for each electron beam optics based on the measurement data of the beam deflection distortion of each electron beam optics and stored in the control circuit.

  In actual drawing, the drawing data of the photomask is previously divided in accordance with the drawing area of each electron beam optical system in the control computer.

  When drawing data is transferred to each electron beam optical system for each main deflection area, the control circuit moves the stage and performs drawing by adding correction data of the drawing position stored in advance to the sent drawing data. . In this way, the stage was moved for each main deflection area, and drawing was performed simultaneously with 8 × 8 electron optical systems.

  As a result of drawing as described above, the joining accuracy was improved at the drawing region boundary of each electron beam optical system, and high-precision drawing could be performed. In addition, since adjustment of the beam deflection distortion of each electron beam optical system and mark detection may be performed for each electron beam optical system, the time required for beam adjustment of the multi-beam drawing apparatus can be greatly shortened.

  In the above embodiment, an array of 8 × 8 electron beams is used. However, the present invention does not limit the number of electron beam arrays. In addition to those shown in the embodiment, the present invention can be used in an electron beam drawing apparatus having an electron beam array number of 100 × 100. Further, the present invention does not limit the drawing apparatus or the drawing method. In addition to the embodiments described above, the present invention can be applied to a drawing apparatus that divides a single beam into a plurality of parts by an aperture, for example. Further, the present invention does not limit the shape or type of the mark. In addition to the above-described embodiment, for example, a convex mark using heavy metal can be applied. In addition, various modifications can be made without departing from the scope of the present invention.

(Third embodiment)
Next, a third embodiment of the present invention will be described. As shown in FIG. 24, each electron beam optical system has a drawing area that overlaps with a drawing area of an adjacent electron beam optical system. At that time, the dose correction is performed so that the portion where the two regions overlap is drawn with a half, and the portion where the two regions overlap with each other is drawn with a dose of 1/4. These steps can improve the drawing accuracy.

  Next, a more specific embodiment of the third embodiment will be described.

(Embodiment 3-1)
The schematic configuration of the multi-beam drawing apparatus used in the present embodiment is as shown in FIG. The drawing apparatus sets the reference position when each electron beam source is at the upper left end of each drawing area.

  As shown in FIG. 19A, the sample 101 is provided with a beam adjustment mark 103. The mark has a cross shape as shown in FIG. 19B, and is formed by engraving a Si substrate by light exposure and plasma etching. The size of the mark is 10 μm on one side, the width is 1 μm, and the depth is 2 μm.

  The drawing possible range in this drawing apparatus is a 154 mm square, and a total of nine electron beam sources are arranged at a pitch of 50 mm, 3 × 3. The beam is main and sub two-stage deflection, and the size of each deflection region is 6 mm for main deflection and 2 mm for sub-deflection. The drawing area of each beam is ± 27 mm with the charged beam source as the center. The drawing area is divided into 81 main deflection areas for drawing.

  In the present embodiment, a 150 mm square photomask is drawn. Prior to drawing, mask data was converted so that one mask was drawn with a plurality of electron beam sources. Assume that multiple writing is performed in units of sub-deflection areas. First, the mask data is divided into nine areas at the pitch of each electron beam source. Around this area, data having a width corresponding to one sub-deflection area is added as shown in FIG. 20 to obtain drawing data for one electron beam source. This data is divided into main deflection areas, further divided into sub deflection areas, and converted into bit data. In the figure, 71 is the size of the mask, 72 is the drawing area, 73 is the main deflection area, and 74 is the sub-deflection area.

  At the time of data conversion, areas drawn twice (85, 86, 87, 88 in the figure) apart from areas drawn with normal exposure amounts, such as 81, 82, 83, 84 in FIG. , 89) The area for quadruple drawing (810, 811 in the figure) was given data for setting the dose. In other words, the dose correction is performed so that the portion where the two regions overlap is drawn by half, and the portion where the two regions overlap is drawn with a dose of 1/4. As a result, even in the region where multiple drawing was performed, the irradiation amount was equivalent to the region where there was no overlap.

  Subsequently, the deflection distortion of each charged beam was adjusted. The deflection distortion was adjusted as follows.

  1) As shown in FIG. 22, the main deflection area of 6 mm is divided into a 500 μm mesh, and the stage is moved so that the reference mark comes on the lattice point. In the figure, 121 is a main deflection area, and 122 is a reference mark.

  2) For the nine beams, the beam is sequentially deflected to detect the mark position.

  3) Move the reference mark and repeat the operations 1) to 2).

  4) The same operation as in 1) to 3) is performed for the sub-deflection area having a size of 2 mm square. The mesh size was 50 μm.

  Subsequently, drawing was performed. First, the stage was moved to the reference position, and the first main deflection area of each charged beam source was drawn. First, the main deflection area was drawn as indicated by 91 in FIG. 23, and then the stage was moved 6 mm to the right, and the second main deflection area was similarly drawn. Thereafter, drawing was sequentially performed according to 92 in the figure.

  As a result of the above, a pattern can be formed with high accuracy in the deflection boundary region of each charged beam source.

  Note that the present invention does not limit the drawing apparatus or the drawing method. In addition to the above-described embodiment, the present invention can be applied to a drawing apparatus that divides one beam into a plurality of parts by an aperture, for example. Further, the present invention does not limit the shape or type of the mark. In addition to the above-described embodiment, for example, a convex mark using heavy metal can be applied. In addition, various modifications can be made without departing from the scope of the present invention.

The figure which shows the optical system of the electron beam drawing apparatus concerning a reference example. The figure which shows the effect at the time of performing mark detection with a some beam. The figure which shows schematic structure of the electron beam drawing apparatus concerning the reference example 1-1. The figure which shows the shape of the mark for beam adjustment in the reference example 1-1. The figure which shows schematic structure of the electron beam drawing apparatus concerning the reference example 1-2. The figure which shows the relationship between the chip | tip and the alignment mark in the reference example 1-2. The figure which shows the structure of the collimator in the reference example 1-3. The figure which shows arrangement | positioning of the electron beam optical system and collimator in Reference Example 1-3. FIG. 5 is a diagram illustrating a procedure of a drawing method according to the first embodiment. FIG. 3 is a diagram illustrating a grouping procedure of electron beam optical systems according to Embodiment 1-1. FIG. 3 is a diagram illustrating a grouping procedure of electron beam optical systems according to Embodiment 1-1. The figure which shows the mode of the grouped electron beam. The figure which shows the structure of the multi-beam drawing apparatus reproduced on the computer program. The figure which shows the mode of the mark detection in 2nd Embodiment. The figure which shows the position measuring method of a reference mark. The figure which shows the position measuring method of a reference mark. The figure for demonstrating the effect of drawing position correction | amendment. FIG. 6 is a diagram illustrating a reference mark position measuring method according to Embodiment 2-1. The figure which shows the beam adjustment mark on a stage, and its position. The figure which shows the drawing area | region per electron beam source string. The figure which shows the overlap of the drawing area | region of each electron beam source. The figure which shows the division | segmentation of the main deflection area | region in the case of deflection distortion adjustment. The figure which shows the order of drawing in a drawing area. The figure which shows an example of multiple drawing. The figure which shows beam deflection distortion. The figure which shows the conventional electron beam optical system. The figure which shows the planar shape and cross-sectional shape of a mark. The figure which shows the mode of a mark detection. The figure which shows the problem at the time of performing mark detection with a some beam. The figure which shows the drawing method of the electron beam drawing apparatus of a multi-beam system. The figure which shows the mode of arrangement | positioning of the ideal reference mark, and the position shift of the mark assumed in reality. The figure which shows the mode of the position shift of the drawing area by the position shift of a reference | standard mark. The figure which shows the mode of the position shift in the drawing area | region boundary of an electron beam optical system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electron gun 2a, 2b, 2c ... Beam adjustment lens system 3 ... Blanking deflector 4 ... Blanking aperture 5a, 5b ... Beam deflection system 6 ... Reflected electron detector 7 ... Electron beam 8 ... From corresponding mark Backscattered electrons 9 ... Backscattered electrons from other marks 10 ... Reference mark 11, 23 ... Collimator 13 ... Electron beam optical system 14 ... Sample 15 ... Sample chamber 16 ... Stage 17 ... Reference mark 18 ... Control circuit 19 ... Control computer 24 ... chip alignment mark 25 ... chip 26 ... wafer 27 ... wafer alignment mark 28 ... electron beam passage hole 29 ... reflected electron opening 30 ... drawing area 31 ... shielding plate (collimator)

Claims (4)

In a multi-beam type charged beam drawing apparatus having a plurality of charged beam optical systems,
A reference mark group provided on the sample stage corresponding to a plurality of charged beam optical systems, means for moving the reference mark group by movement on the sample stage, and scanning the charged beam on the moved reference mark, Means for measuring the position of each reference mark, means for storing the relative positional relationship of each measured reference mark, and the drawing region of each charged beam based on the stored relative positional relationship of each reference mark A charged beam drawing apparatus comprising: means for correcting a position; and means for drawing based on the corrected drawing position. A multi-beam type charged beam drawing apparatus having a plurality of charged beam optical systems, wherein a drawing position is corrected using a reference mark group provided on a sample stage corresponding to each charged beam optical system. In the charged beam drawing method,
A step of performing mark position detection with a plurality of charged beam optical systems, a step of performing mark position detection using a reference mark of an adjacent charged beam optical system, a step of calculating a relative positional relationship between reference mark groups, A charged beam drawing method comprising: a step of correcting a position of a drawing region of each charged beam optical system based on the calculation result; and a step of drawing at the corrected drawing position. In a multi-beam type charged beam drawing method for drawing using a plurality of charged beam sources,
Adjusting the deflection distortion of each beam optical system in advance using a reference mark provided on the sample for each charged beam optical system;
Of the beam optical systems in which the deflection distortion is adjusted, drawing so that the deflection boundary regions of adjacent beam optical systems have overlapping regions ;
Charged beam lithography method, which comprises a.   The charged beam drawing method according to claim 3, wherein the dose correction of the overlapping region is performed.

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